Good stuffs everyone. I've been looking through CS's whilst grading an almost countless sea of tests and essays. There are characters I really enjoy, characters that I feel could use retooling, and characters that I feel need more information or more fleshing out.
One thing to consider is why your character would go on an adventure? Happy-go-lucky types are okay, but even Marlowe will have a drive or a goal to reach far beyond his simple "I want to see the world" mindset. Revenge, lost honor, forbidden knowledge, love; all of these are things are what give characters purpose beyond simple meandering.
A member of my secret Illuminati council said it best: what's all the skill in the world against the drive of a desperate man or woman? What drives people to seek out ancient treasure and certain doom? For some it's fool's luck and a naive sense of adventure, but others have starving families, sick children, dead parents, etc to spur them on.